In a W-CDMA mobile communication system, a location registration area ID (Location Area ID) is assigned to each of cells.
A mobile station is configured to perform processing of location registration for a location registration server when being turned on or when detecting change in the location registration area ID included in broadcast information transmitted from each cell.
When a call addressed to the mobile station comes in, an exchange inquires the location registration server of a location registration area in which the mobile station exists. Then, a paging signal is transmitted to the location area and thereby the mobile station is notified of the incoming call.
Meanwhile, it is assumed in a conventional mobile communication system that a small radio base station for home use such as a femto radio base station is provided.
For example, when many femto radio base stations are provided in a crowded residential area, an apartment house, or the like, the following problem occurs. When different location registration area IDs are assigned respectively to home cells managed by all the femto radio base stations, the location registration processing is performed frequently by mobile stations.
In order to solve the above problem, an operation is performed in which the same location registration area ID is assigned to a cell group including multiple home cells.
However, the above-described mobile communication system is configured to transmit the paging signal to all the cells which are assigned the same location area ID when a call addressed to the mobile station comes in. Accordingly, the paging signal is transmitted to the home cell which is not accepting access from the mobile station. Thus, there are problems of wasteful consumption of radio resource and wasteful consumption of power in the radio base station due to redundant transmission of the paging signal.